Media and multimedia provision to client over different networks have increased tremendously the last few years. Today, Internet is employed by numerous users for accessing and downloading media, e.g. in the form of video and audio streams or files, from media servers. This media provision has also emerged in radio-based mobile communications networks. There is currently a very big interest in using mobile networks for multimedia or TV content. This is often referred to as Mobile-TV in the art. This media provision in the mobile networks is today mainly available through unicast transport. However, at the moment, broadcast/multicast delivery methods for Mobile-TV are under development. Examples of such standardisation efforts are 3GPP Multimedia Broadcast/Multicast Services (MBMS) and European Telecommunications Standards Institute (ETSI) Digital Video broadcasting-Handheld (DVB-H).
In line with this increasing demand for media provision in different wired and wireless communications networks, there is on-going work in the development of streaming and downloading servers available in wireless networks for providing media content to requesting clients. There is a general trend towards transparent and flexible streaming/downloading servers, implying that the servers should basically consist of a multitude of “standard” modules or programmes performing different media managing functions. The input media content to these functions is then provided together with instructions of how the modules/programmes should process the content. This will provide a more flexible media provision as compared to usage of fixed, pre-defined media processing in the servers.
Together with the development of flexible streaming/downloading servers, development is taking place in the area of how error correction can be introduced in the media streams. The multicast/broadcast transmissions are unidirectional and addressing a high number of receiving clients simultaneously. Traditional unicast reliability schemes, such as Automatic Repeat Request (ARQ), are not scalable to serve the high number of receivers of multicast/broadcast transmissions.
Thus, there is a need for introduction of a reliability scheme in connection with multicast/broadcast media transmission. The introduction of such a reliability scheme should also be in the line with trend of flexible streaming and downloading server solutions.